The present invention relates to analog signal monitoring systems and methods and in particular, to a power and environmental condition monitoring system and method that monitors power and environmental conditions at a remote site.
As a result of the widespread use of computers and other microprocessor-based equipment, the quality of power and other environmental conditions at sites having such equipment has become increasingly important. Utility companies deliver electric power to customer sites as an alternating current (AC) voltage through an secondary power distribution system. Various distribution system and environmental factors, however, can cause power line transients, such as spikes, surges, or sags, and can cause blackouts, brownouts, or other distribution system problems that greatly affect the quality of power received by the customer at a site. Electronic equipment, such as computers and other equipment with microprocessors, are susceptible to damage and/or a faulty operation as a result of power line transients and other poor power quality conditions. The quality of power is likely to become increasingly important as the utility industry is deregulated and the utility companies compete more aggressively for power users.
One attempt at improving the quality of power at a site has been to install a power conditioner. This solution, however, often provides a false sense of security. Power protection manufacturers typically design power conditioner systems assuming that a site meets the National Electrical Code for safety. Power protection manufacturers also assume that a site has good, solid earth ground and only one grounding path. With substandard grounding, many power conditioners will not provide optimum protection and the resulting impulse let through and high frequency noise will adversely affect system performance. Thus, power conditioners may suffer from the same problems caused by poor power quality. Also some power conditioners do not address all potential power quality problems, such as voltage regulation issues or outages. The typical power conditioner is designed to filter high frequency events only leaving the system vulnerable to low frequency events, such as power factor correction and harmonics. Power conditioning also fails to address numerous other issues that can affect the equipment reliability and performance, such as temperature, humidity, air quality, vibration and numerous other environmental conditions.
Another solution is to use power monitoring equipment to monitor the power quality at a site either before installing electronic equipment or after problems occur with the electronic equipment. Conventional power monitoring equipment suffers from numerous drawbacks. Existing power monitoring equipment is overly complex, expensive, and typically requires a special setup, depending upon the site. In addition to not being user-friendly, the existing systems are not capable of organizing the data and presenting the data in a useful format. Although existing systems are capable of gathering large amounts of data, these systems are unable to adequately process, save and transmit that data for use in generating power quality reports that facilitate correcting the problems. In these systems, the vast amount of data must often be recorded and sent out for processing, and a report is mailed at a much later time.
In addition to systems that generate too much data, some existing systems generate too little data such that a determination cannot be made as to why certain power events might have occurred. Existing power monitoring equipment also does not have the capability of monitoring multiple channels including extensive monitoring of environmental conditions as well as power conditions and power events. Traditional power monitors are also not set up to do interactive tests (e.g., input and output of a UPS or power conditioner, data gathering of the UPS status log, or a line impedance test for measuring the line resistance). the ability to provide a more comprehensive data gathering for all of the site""s conditions has traditionally been lacking.
Accordingly, a system and method is needed for monitoring power and environmental conditions that is easier to set up and operate. A power and environmental condition monitoring system and method is also needed that improves the processing, storage and transfer of data using data compression techniques. A power and environmental condition monitoring system and method is also needed that is capable of presenting analyzed data in a format that allows a customer to understand the problem and to attempt to correct that problem. A power and environmental condition monitoring system and method is also needed that monitors multiple channels in real time, including environmental condition signals, and that has the ability to run interactive tests and gather data from remote devices (i.e., UPS system logs).
The present invention features a power and environmental condition monitoring system, for monitoring power and environmental conditions at a site. The system comprises at least one analog signal receiver including a plurality of analog signal channels for receiving a plurality of analog measurement signals representing power and environmental conditions, for converting the analog measurement signals into digital signals including digital signal data, and for buffering the digital signal data. The analog signal channels include at least one high/low frequency voltage channel for monitoring voltage signals including high frequency voltage events and at least one configurable multi-purpose channel for monitoring low frequency analog measurement signals. At least one digital signal processor, connected to the analog receiver, reads the digital signal data buffered by the analog signal receiver and processed the digital signal data. The digital signal processor processes the digital signal data by logging at least some of the digital signal data, and wherein digital signal processor processes the digital signal data by analyzing at least some of the digital signal data to detect a pattern consistent with an event and by logging selected values of the digital signal data sufficient to define said event. A post-processing system, connected to the digital signal processor, stores and post processes processed digital signal data received from the digital signal processor.
The post-processing system preferably includes a communications device for communicating with a remote location and for transmitting said processed digital signal data to the remote location. In one embodiment, the post-processing system is implemented on a personal computer. In this embodiment, the analog signal receiver includes at least one analog board connected to the personal computer, and the digital signal processor includes at least one digital signal processor board connected to the personal computer. The multi-purpose channel is preferably configurable to monitor one of a low frequency voltage signal, a current signal, and an environmental condition signal and the personal computer preferably includes software for configuring the multi-purpose channel.
The digital signal processor preferably includes a sample digital signal processor, connected to the analog signal receiver, and a process digital signal processor, connected to the sample digital signal processor. The sample digital signal processor reads the digital signal data buffered by the analog signal receiver and addresses and buffers the digital signal data. The process digital signal processor receives the digital signal data transmitted by the sample digital signal processor and processes the digital signal data. The sample digital signal processor reads digital signal data buffered by the analog signal receiver using an interrupt, and polls the digital signal data buffered by the analog signal receiver to read the digital signal data representing the high frequency events.
The present invention also features a method of monitoring power and environmental conditions. The method comprises: receiving analog voltage signals over high/low frequency voltage inputs and receiving analog measurement signals over multi-purpose inputs; converting the analog voltage signals and the analog measurement signals into low frequency digital data; monitoring the analog voltage signals to detect high frequency voltage signals representing high frequency voltage events; converting the high frequency voltage signals into high frequency digital data; processing the low frequency digital data by logging selected values of the low frequency digital data into at least one data log file; and processing the low frequency digital data and the high frequency digital data by detecting events and logging the events in an event log file.
The present invention also features an analog signal receiver for use in a power and environmental condition monitoring system. The analog signal receiver comprises a plurality of analog signal inputs including high/low voltage signal inputs for receiving voltage signals and multi-purpose inputs for receiving low frequency analog measurement signals. A plurality of isolated measurement circuits measure the voltage signals received on said high/low voltage signal inputs. Analog signal processing circuitry processes the voltage signals and the low frequency analog measurement signals. A multiplexer multiplexes the voltage signals and the analog measurement signals into a multiplexed low frequency analog signal. A low frequency A/D converter converts the multiplexed low frequency analog signal to low frequency digital signal data. A low frequency buffer buffers the low frequency digital signal data.
The analog signal receiver further includes a high frequency voltage event detector for detecting high frequency voltage events. At least one high frequency A/D converter converts the high frequency voltage events to high frequency voltage digital data. A high frequency buffer buffers the high frequency voltage digital data.
Each isolated measurement circuit preferably includes an isolation amplifiers and an isolated signal transmitter connected to the isolation amplifier. The isolated signal transmitter can include a linear optocoupler, a transformer coupler, and a capacitive coupler. The high frequency voltage event detector preferably includes a peak detect circuit.
The present invention also features a system and method for processing data in a power and environmental condition monitoring system. The method comprises receiving high frequency data and low frequency data, representing voltage signals and condition signals. The method also comprises generating data log entries each including at least a date/time stamp and at least some of the low frequency data and logging the data log entry in a data log. The method further comprises classifying the high frequency and low frequency data to determine an event classification; analyzing the high frequency and low frequency data based upon the event classification and selecting sufficient data values to define the event; generating an event data log entry; and logging the event data log entry into an event log.